HD Partitions - General Question

[Bob Gir.]

    Just got my La Cie160GB external HD (found via DealMac for $146,
shipping included).

    I will be using it to back up whatever iMac I get when the new ones come
out and a G4 iBook which my wife will be getting.
    
    I _always_ seem to come up with the wrong scheme for partitioning these
things and of course re-partitioning means wiping clean the whole drive
which can be a pain.

    Given that the hard drive on my current B&W desktop is 4.24 GB in size
and that probably photo files are the only things that are going to chew up
significant amounts of additional disk space (I am not into music on my
computer), what would more experienced folks suggest for a partition scheme?

    Just off the top of my head, I was considering three partitions of equal
size:  one would hold the backup for the iMac, another the backup for the
iBook, the third for storage of odds and ends like photo files, downloaded
System upgrades from Apple, for use in the event that we ever had to install
the system software from the CDs, etc.

    Your input welcome,
    bob